Shift by wire shifting devices with mechanical parking engagement at a position in which vehicle transmission is blocked (Park position, or P position) require the provision of a mechanism to lock the gearshift at said position in order to block the vehicle transmission when parked and not to transmit any movement to the brake cable when the gearshift lever is operated in the rest of the unblocked transmission gearshift positions (Reverse, Neutral, Drive positions, or R, N, D positions).
In this respect, shifting devices for motor vehicles are known in the art comprising a selector lever that can be moved relative to a fixed part, such as a shift gate, for shifting between the P position and the other R, N, D operating positions. Some known shifting devices are provided with a selector lever lock for preventing the gearshift lever to be moved when in said P position in which the vehicle transmission is blocked.
One example of a lock for the gearshift lever comprises a detent mechanism for releasably coupling the shift lever and a detent plate attached on the shift gate. The detent mechanism is manually released from the detent plate and the shift lever so that the shift lever can be repositioned.
A further example of such a lock includes a locking lever that is pivotally disposed relative to the detent plate and connected to the vehicle ignition lock mechanism for pivotal movement to a locking position relative to the detent mechanism. This prevents release of the shift lever when the ignition lock mechanism is actuated to the locking position with the shift lever in the P position. Such an example is disclosed, for example, in US2002170376 in which means for mechanical coupling between the gearshift lever and the automatic transmission are provided. The P position can be then released in case of power failure. In this document, the locking device comprises an electromagnetic unlocking device. This unlocking device acts on a lever arm against the strength of a spring. The lever arm has a hook at one free end thereof for locking the gearshift lever when in the P position allowing gearshift release when electromagnetic unlocking device is powered, for example when ignition is turned on, such that it can be moved into all the operating positions.
WO2008106950 shows a further example of a gearshift lever lock for locking the selector lever in the P position. An electromagnetic actuator is provided that is activated when the user operates a push button in the selector lever. This makes a locking rocker to be disengaged from gearshift lever such that it can be moved out of the P position into one of said operating positions.
Although prior art systems are effective, they are bulky, complex, expensive and noisy when in use.